Investigators release cockpit voice recording from Alaska Airlines crash

The jackscrew, left and gimbal nut from Alaska Airlines Flight 261

WASHINGTON (Reuters) -- "We're in much worse shape now," the captain of Alaskan Airlines Flight 261 said about nine minutes before losing a battle to keep the plane in the air on January 31, a transcript issued Wednesday showed.

Capt. Ted Thompson and first officer Bill Tansky faced an escalating crisis controlling the MD-83 twinjet's horizontal stabilizer mounted on the tail, with Thompson remarking after hearing a big bang: "I think the stab trim thing is broke."

The National Transportation Safety Board issued the cockpit voice recording transcript covering the last half hour of the flight at the start of a four-day public hearing into the crash off California that killed all 88 people on board.

INTERACTIVE RESOURCES Zoom in: How the MD-83 stabilizer works Timeline of recent crashes Flight 261 altitude data Image gallery: The crash of Flight 261 Flight 261 background Facts about Alaska Airlines

Much of the hearing will focus on the design and maintenance of the jackscrew mechanism that controls the stabilizer, used to control the plane's nose-up or nose-down attitude.

Safety board investigators are concerned Alaska Airlines may not have lubricated the jackscrew assembly adequately, mixing two incompatible greases together.

A preliminary report by the Naval Air Warfare Center said grease from the accident plane's jackscrew showed a mixture of Aeroshell Grease 33 and Mobil Grease 28.

"As a general rule, two incompatible greases should not be mixed because an inferior product could result," Navy chemist Todd Standish wrote.

The jackscrew was found on the seabed off Point Mugu, north of Los Angeles, with threads from the gimbal nut wrapped around it and no visible evidence of grease on its working surfaces.

Safety board member John Hammerschmidt, who will chair the hearing, said the aim was to collect information to assist in the investigation. A later meeting would determine the probable cause of the crash.

Alaska Airlines is the nation's 10th largest carrier and a subsidiary of Seattle-based Alaska Air Group.

Boeing Co. in 1997 bought McDonnell Douglas which designed the MD-80 and related aircraft that include the DC-9, MD-90 and Boeing 717.

Flight 261 was a scheduled service from Puerto Vallarta, Mexico, to Seattle, with a stop in San Francisco.

But just over two hours out from Puerto Vallarta, the 31-minute recording starts with the pilots trouble-shooting the stabilizer problem with Alaska's maintenance base in Seattle.

The flight crew have also requested a diversion to Los Angeles airport.

Twelve minutes before the crash, the situation rapidly turns into a crisis as the stabilizer goes into a full-nose down position after the captain refers to moving a switch.

Two faint thumps are heard on the tape and the plane goes into a steep dive from 31,000 feet to 24,000 feet that exceeds the plane's maximum allowable airspeed of 343 knots. "We've lost vertical control of our airplane," Thompson tells air controllers before leveling out.

Thompson tells Tansky that they are in worse shape now than before, believing the stabilizer has come to rest at its full nose-down angle.

Thompson tries to calm passengers, saying "I don't anticipate any big problems once we get a couple of sub-systems on the line."

The flight crew advise controllers they need time to reconfigure the plane to land but want to make sure they can control the jet. "I'd like to do that out here over the bay if I may," Thompson says.

With just under four minutes left on the recording, a flight attendant comes to the cockpit to report "a big bang back there." Thompson says he heard it too.

The pilots make two attempts to extend the slats and flaps to slow the plane for landing but with under two minutes of the recording left, a faint thump is followed by a loud noise.

"Mayday," says Tansky followed by Thompson saying the plane is upside down, "we are inverted."

The two pilots trade instructions for working the controls but the effort is in vain as the plane takes a final dive from 18,000 feet.

"Ah here we go," Thompson says just at the end of the recording.

Copyright 2000 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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